This invention relates to semiconductor devices, and more particularly to metal contacts and interconnections for semiconductor integrated circuits.
In manufacture of VLSI semiconductor devices, a thin metal coating such as aluminum is deposited and patterned to create contacts and interconnections. Problems occur in thinning of the metal at near-vertical sidewalls of holes in thick insulator layers where the metallization pattern makes contact to silicon regions or to polysilicon layers. Thinner metal at these sidewalls or other steps results in higher resistance and a propensity for electro-migration failures. Heretofore, the steepness of the sidewalls has been minimized by a "reflow" process but this necessitates undesirable high temperature operations and larger geometries.
It is the principal object of this invention to provide an improved process for making metal contacts and interconnections for semiconductor integrated circuits. Another object is to provide improved semiconductor devices with metallization patterns avoiding thinning at steps and contact apertures. A further object is to provide improved step coverage and lower resistance for metallization of semiconductor devices.